Paget's disease of bone appears to be unusually common in Australia. It has been noted, however, only in those of Anglo-Saxon origin who have either been born in Australia or who have emigrated there from the United Kingdom. It is known to be extremely rare and possibly unknown in the Chinese. In Australia, the disease is usually symptomless and pain is a rare feature—pathological fractures occur quite commonly, most often in the subtrochanteric region of the femur. The incidence of malignant change is considered to be very low in Australia and is probably less than 1 per cent. A series of twenty-nine bone tumors arising in Paget's disease (twelve not proved by biopsy), that were treated in the teaching hospitals of Sydney during 1950 through 1959, has been reviewed. In addition two more recent personal cases are reported, making a total of thirty-one. One-third of these neoplasms developed in the upper arm or shoulder girdle and nearly one patient in four had a tumor in the skull. Several patients had multiple malignant lesions. In five cases there was a history of trauma prior to the development of a sarcoma, but there was no evidence that a malignant change developed as the result of a fracture or surgical intervention. All of these tumors were osteogenic sarcomata except for one fibrosarcoma, one chondrosarcoma, and one giant-cell tumor which have been reported in detail together with a soft-tissue tumor of unknown pathology with which the patient survived eight years after roentgen therapy. A family is reported in which two brothers had sarcomata in Paget's disease. Treatment consisted in amputation, deep roentgen therapy, and palliative measures; the results are noted.